Phase I clinical evaluation of a neutralizing monoclonal antibody against epidermal growth factor receptor in advanced brain tumor patients: preliminary study

EGFR, the Lazarus target for precision oncology in glioblastoma

The Lazarus effect is a rare condition that happens when someone seemingly dead shows signs of life. The epidermal growth factor receptor (EGFR) represents a target in the fatal neoplasm glioblastoma (GBM) that through a series of negative clinical trials has prompted a vocal subset of the neuro-oncology community to declare this target dead. However, an argument can be made that the core tenets of precision oncology were overlooked in the initial clinical enthusiasm over EGFR as a therapeutic target in GBM. Namely, the wrong drugs were tested on the wrong patients at the wrong time. Furthermore, new insights into the biology of EGFR in GBM vis-à-vis other EGFR-driven neoplasms, such as non-small cell lung cancer, and development of novel GBM-specific EGFR therapeutics resurrects this target for future studies. Here, we will examine the distinct EGFR biology in GBM, how it exacerbates the challenge of treating a CNS neoplasm, how these unique challenges have influenced past and present EGFR-targeted therapeutic design and clinical trials, and what adjustments are needed to therapeutically exploit EGFR in this devastating disease.

Depatuxizumab mafodotin in EGFR-amplified newly diagnosed glioblastoma: A phase III randomized clinical trial

BACKGROUND

Approximately 50% of newly diagnosed glioblastomas (GBMs) harbor epidermal growth factor receptor gene amplification (EGFR-amp). Preclinical and early-phase clinical data suggested efficacy of depatuxizumab mafodotin (depatux-m), an antibody-drug conjugate comprised of a monoclonal antibody that binds activated EGFR (overexpressed wild-type and EGFRvIII-mutant) linked to a microtubule-inhibitor toxin in EGFR-amp GBMs.

METHODS

In this phase III trial, adults with centrally confirmed, EGFR-amp newly diagnosed GBM were randomized 1:1 to radiotherapy, temozolomide, and depatux-m/placebo. Corneal epitheliopathy was treated with a combination of protocol-specified prophylactic and supportive measures. There was 85% power to detect a hazard ratio (HR) ≤0.75 for overall survival (OS) at a 2.5% 1-sided significance level (ie traditional two-sided p ≤ 0.05) by log-rank testing.

RESULTS

There were 639 randomized patients (median age 60, range 22-84; 62% men). Prespecified interim analysis found no improvement in OS for depatux-m over placebo (median 18.9 vs. 18.7 months, HR 1.02, 95% CI 0.82-1.26, 1-sided p = 0.63). Progression-free survival was longer for depatux-m than placebo (median 8.0 vs. 6.3 months; HR 0.84, 95% confidence interval [CI] 0.70-1.01, p = 0.029), particularly among those with EGFRvIII-mutant (median 8.3 vs. 5.9 months, HR 0.72, 95% CI 0.56-0.93, 1-sided p = 0.002) or MGMT unmethylated (HR 0.77, 95% CI 0.61-0.97; 1-sided p = 0.012) tumors but without an OS improvement. Corneal epitheliopathy occurred in 94% of depatux-m-treated patients (61% grade 3-4), causing 12% to discontinue.

CONCLUSIONS

Interim analysis demonstrated no OS benefit for depatux-m in treating EGFR-amp newly diagnosed GBM. No new important safety risks were identified.

Chimeric Antigen Receptor T Cells With Modified Interleukin-13 Preferentially Recognize IL13Rα2 and Suppress Malignant Glioma: A Preclinical Study

Background

Interleukin-13 receptor α 2 (IL13Rα2) is a promising tumor-directed antigen of malignant glioma (MG). Here, we examine the efficacy and safety of T cells containing a YYB-103 chimeric antigen receptor (CAR) that can preferentially bind to IL13Rα2 on MG cells.

Methods

IL13 was modified on the extracellular domain by substitution of amino acids with E13K, R66D, S69D, and R109K and stably transfected into human T cells using a retroviral vector. The in vitro efficacy of YYB-103 CAR T cells was tested in cell lines with differing IL13Rα1 and IL13Rα2 expression. The in vivo efficacy of intracerebroventricular (i.c.v.) and intravenous (i.v.) routes of YYB-103 CAR T-cell administration were tested in orthotopic MG mouse models. Immunohistochemical staining of MG was performed using WHO grade 3/4 surgical specimens from 53 patients. IL13Rα2 expression was quantified by H-score calculated from staining intensity and percentage of positive cells.

Results

Binding affinity assay of YYB-103 verified apparently nil binding to IL13Rα1, which was more selective than previously reported IL13 modification (E13Y). YYB-103 CAR T cells showed selective toxicity toward co-cultured U87MG (IL13Rα1+/IL13Rα2+) cells but not A431 (IL13Rα1+/IL13Rα2-) cells. Consistently, YYB-103 CAR T cells suppressed tumor growth in nude mice receiving orthotopic injection of U87 MG cells. Both i.c.v. and i.v. injections of YYB-103 CAR T cells reduced tumor volume and prolonged overall survival of tumor-bearing mice. The median H-score for IL13Rα2 in patient-derived MG tissue was 5 (mean, 57.5; SD, 87.2; range, 0 to 300).

Conclusion

This preclinical study demonstrates the efficacy of IL13Rα2-targeted YYB-103 CAR T cells against MG cells. The use of modified IL13 to construct a CAR facilitated the selective targeting of IL13Rα2-expressing MG cells while sparing IL13Rα1-expressing cells. Notably, YYB-103 CAR T cells exhibited effective blood-brain barrier crossing, suggesting compatibility with i.v. administration rather than intracranial injection. Additionally, the high H-score for IL13Rα2 in glioblastoma, especially in conjunction with the poor prognostic markers of wild-type isocitrate dehydrogenase-1 (IDH-1) and unmethylated O6-methyl guanine methyl-transferase (MGMT), could be used to determine the eligibility of patients with recurrent glioblastoma for a future clinical trial of YYB-103 CAR T cells.

Overcoming the Blood-Brain Barrier: Successes and Challenges in Developing Nanoparticle-Mediated Drug Delivery Systems for the Treatment of Brain Tumours

High-grade gliomas are still characterized by a poor prognosis, despite recent advances in surgical treatment. Chemotherapy is currently practiced after surgery, but its efficacy is limited by aspecific toxicity on healthy cells, tumour cell chemoresistance, poor selectivity, and especially by the blood–brain barrier (BBB). Thus, despite the large number of potential drug candidates, the choice of effective chemotherapeutics is still limited to few compounds. Malignant gliomas are characterized by high infiltration and neovascularization, and leaky BBB (the so-called blood–brain tumour barrier); surgical resection is often incomplete, leaving residual cells that are able to migrate and proliferate. Nanocarriers can favour delivery of chemotherapeutics to brain tumours owing to different strategies, including chemical stabilization of the drug in the bloodstream; passive targeting (because of the leaky vascularization at the tumour site); inhibition of drug efflux mechanisms in endothelial and cancer cells; and active targeting by exploiting carriers and receptors overexpressed at the blood–brain tumour barrier. Within this concern, a suitable nanomedicine-based therapy for gliomas should not be limited to cytotoxic agents, but also target the most important pathogenetic mechanisms, including cell differentiation pathways and angiogenesis. Moreover, the combinatorial approach of cell therapy plus nanomedicine strategies can open new therapeutical opportunities. The major part of attempted preclinical approaches on animal models involves active targeting with protein ligands, but, despite encouraging results, a few number of nanomedicines reached clinical trials, and most of them include drug-loaded nanocarriers free of targeting ligands, also because of safety and scalability concerns.

En Plaque Meningiomas: A Narrative Review

Background  En plaque meningiomas are a rare subtype of meningiomas that are frequently encountered in the spheno-orbital region. Characterized by a hyperostotic and dural invasive architecture, these tumors present unique diagnostic and treatment considerations. Objective  The authors conduct a narrative literature review of clinical reports of en plaque meningiomas to summarize the epidemiology, clinical presentation, diagnostic criteria, and treatment considerations in treating en plaque meningiomas. Additionally, the authors present a case from their own experience to illustrate its complexity and unique features. Methods  A literature search was conducted using the MEDLINE database using the following terminology in various combinations: meningioma , meningeal neoplasms, en plaque , skull base , spheno-orbital, and sphenoid wing . Only literature published in English between 1938 and 2018 was reviewed. All case series were specifically reviewed for sufficient data on treatment outcomes, and all literature was analyzed for reports of misdiagnosed cases. Conclusion  En plaque meningiomas may present with a variety of symptoms according to their location and degree of bone invasion, requiring a careful diagnostic and treatment approach. While early and aggressive surgical resection is generally accepted as the optimal goal of treatment, these lesions require an individualized approach, with further investigation needed regarding the role of new therapies.

Emerging Medical Treatments for Meningioma in the Molecular Era

Meningiomas are the most common type of primary central nervous system tumors. Approximately, 80% of meningiomas are classified by the World Health Organization (WHO) as grade I, and 20% of these tumors are grade II and III, considered high-grade meningiomas (HGMs). Clinical control of HGMs, as well as meningiomas that relapse after surgery, and radiation therapy is difficult, and novel therapeutic approaches are necessary. However, traditional chemotherapies, interferons, hormonal therapies, and other targeted therapies have so far failed to provide clinical benefit. During the last several years, next generation sequencing has dissected the genetic heterogeneity of meningioma and enriched our knowledge about distinct oncogenic pathways driving different subtypes of meningiomas, opening up a door to new personalized targeted therapies. Molecular classification of meningioma allows a new design of clinical trials that assign patients to corresponding targeted agents based on the tumor genetic subtypes. In this review, we will shed light on emerging medical treatments of meningiomas with a particular focus on the new targets identified with genomic sequencing that have led to clinical trials testing novel compounds. Moreover, we present recent development of patient-derived preclinical models that provide platforms for assessing targeted therapies as well as strategies with novel mechanism of action such as oncolytic viruses.

A novel recombinant anti-epidermal growth factor receptor peptide vaccine capable of active immunization and reduction of tumor volume in a mouse model

Over-expression of epidermal growth factor receptor (EGFR) has been reported in a number of human malignancies. Strong expression of this receptor has been associated with poor survival in many such patients. Active immunizations that elicit antibodies of the desired type could be an appealing alternative to conventional passive immunization. In this regard, a novel recombinant peptide vaccine capable of prophylactic and therapeutic effects was constructed. A novel fusion recombinant peptide base vaccine consisting of L2 domain of murine extra-cellular domain-EGFR and EGFR mimotope (EM-L2) was constructed and its prophylactic and therapeutic effects in a Lewis lung carcinoma mouse (C57/BL6) model evaluated. Constructed recombinant peptide vaccine is capable of reacting with anti-EGFR antibodies. Immunization of mice with EM-L2 peptide resulted in antibody production against EM-L2. The constructed recombinant peptide vaccine reduced tumor growth and increased the survival rate. Designing effective peptide vaccines could be an encouraging strategy in contemporary cancer immunotherapy. Investigating the efficacy of such cancer immunotherapy approaches may open exciting possibilities concerning hyperimmunization, leading to more promising effects on tumor regression and proliferation.

Small Molecule and Monoclonal Antibody Therapies in Neurooncology

Background:

The prognosis for most patients with primary brain tumors remains poor. Recent advances in molecular and cell biology have led to a greater understanding of molecular alterations in brain tumors. These advances are being translated into new therapies that will hopefully improve the prognosis for patients with brain tumors.

Methods:

We reviewed the literature on small molecule targeted agents and monoclonal antibodies used in brain tumor research and brain tumor clinical trials for the past 20 years.

Results:

Brain tumors commonly express molecular abnormalities. These alterations can lead to the activation of cell pathways involved in cell proliferation. This knowledge has led to interest in novel anti-brain-tumor therapies targeting key components of these pathways. Many drugs and monoclonal antibodies have been developed that modulate these pathways and are in various stages of testing.

Conclusions:

The use of targeted therapies against brain tumors promises to improve the prognosis for patients with brain tumors. However, as the molecular pathogenesis of brain tumors has not been linked to a single genetic defect or target, molecular agents may need to be used in combinations or in tandem with cytotoxic agents. Further study of these agents in well-designed cooperative clinical trials is needed.

Inhibition activity of a disulfide-stabilized diabody against basic fibroblast growth factor in lung cancer

The over-expression of basic fibroblast growth factor (bFGF) plays a crucial role in the development, invasion and metastasis of lung cancer. Therefore, neutralizing antibodies against bFGF may inhibit the growth of lung cancer. In this study, a Disulfide-stabilized diabody (ds-Diabody) against bFGF was constructed by site-directed mutation and overlap extension PCR (SOE-PCR) at the position of VH44 and VL100 in the scFv. The ds-Diabody was constructed and expressed in Pichia pastoris. We found that the ds-Diabody against bFGF could efficiently suppress the proliferation, migration and invasion of human lung cancer A549 cells in vitro. Moreover, in A549 cells, the ds-Diabody against bFGF could inhibit bFGF-induced activation of downstream signaling regulators, such as phospho-Akt and phospho-MAPK. In the nude mouse xenograft model of lung cancer, the ds-Diabody against bFGF could significantly inhibit tumor growth and decrease the densities of micro-vessels and lymphatic vessels in tumor tissue. Our data indicate that the ds-Diabody against bFGF could effectively suppress the lung cancer growth through blockade of bFGF signaling pathway and inhibition of tumor angiogenesis, which may make it a potential therapeutic candidate antibody drug for human lung cancer therapy.

Determination of the starting dose in the first-in-human clinical trials with monoclonal antibodies: a systematic review of papers published between 1990 and 2013

A systematic review was performed to evaluate how the maximum recommended starting dose (MRSD) was determined in first-in-human (FIH) studies with monoclonal antibodies (mAbs). Factors associated with the choice of each MRSD determination method were also identified. PubMed was searched for FIH studies with mAbs published in English between January 1, 1990 and December 31, 2013, and the following information was extracted: MRSD determination method, publication year, therapeutic area, antibody type, safety factor, safety assessment results after the first dose, and number of dose escalation steps. Seventy-nine FIH studies with mAbs were identified, 49 of which clearly reported the MRSD determination method. The no observed adverse effects level (NOAEL)-based approach was the most frequently used method, whereas the model-based approach was the least commonly used method (34.7% vs 16.3%). The minimal anticipated biological effect level (MABEL)- or minimum effective dose (MED)-based approach was used more frequently in 2011–2013 than in 1990–2007 (31.6% vs 6.3%, P=0.036), reflecting a slow, but steady acceptance of the European Medicines Agency’s guidance on mitigating risks for FIH clinical trials (2007). The median safety factor was much lower for the MABEL- or MED-based approach than for the other MRSD determination methods (10 vs 32.2–53). The number of dose escalation steps was not significantly different among the different MRSD determination methods. The MABEL-based approach appears to be safer and as efficient as the other MRSD determination methods for achieving the objectives of FIH studies with mAbs faster.

Multiple dose toxicity study of the humanized anti-epidermal growth factor receptor monoclonal antibody h-R3 intravenously administered to Cercopithecus aethiops sabaeus monkeys

The h-R3 is a humanized growth factor receptor monoclonal antibody (mAb) in development for the treatment of head and neck tumours in which malignant cells overexpress the Epidermal Growth Factor receptor. The present study was designed to evaluate the toxicity of repeated intravenous doses of the h-R3 mAb in a relevant species demonstrated by the avidin-biotin-peroxidase immunohistochemical (IHC) technique in skin biopsy samples from three Cercopithecus aethiops sabaeus monkeys (green monkeys). Additionally, 18 green monkeys were daily intravenously treated during 14 consecutive days. Monkeys were distributed into three experimental groups with three animals of each sex in each group. Group I received saline solution and served as control group; group II received 2.85 mg/kg of h-R3 mAb; and group III received 11.4 mg/kg of the h-R3 mAb. During the study there were no deaths, neither pathological clinical signs, or variations in the corporal weight curve. The electroneurophysiological and sanguine chemistry results did not evidence alterations related to the assay substance. Areas of haematomas, haemorrhages and inflammation, probably related with the administration procedure, were observed at the administration zones of all animals; this fact could also explain the increase in the neutrophil count of all animals at the end of the study. The electrocardiography study showed that in the 14 days of the study one female monkey, from the higher dose group, shifted its cardiac axis from +60° to +120°; this finding could be interpreted as a right ventricular elongation due to the relative high daily administered volume.

It is concluded that doses up to 11.4 mg/kg of h-R3, intravenously administered during 14 consecutive days to Cercopithecus aethiops sabaeus monkeys do not produce considerable toxic effects in the studied system.

Targeted Therapy in Locally Advanced and Recurrent/Metastatic Head and Neck Squamous Cell Carcinoma (LA-R/M HNSCC)

Surgery and radiotherapy are the standard treatment options for patients with squamous cell carcinoma of the head and neck (SCCHN). Chemoradiotherapy is an alternative for patients with locally advanced disease. In recurrent/metastatic disease and after progression to platin-based regimens, no standard treatments other than best supportive care are currently available. Most SCCHN tumours overexpress the epidermal growth factor receptor (EGFR). This receptor is a tyrosine-kinase membrane receptor that has been implicated in angiogenesis, tumour progression and resistance to different cancer treatments. In this review, we analysed the different drugs and pathways under development to treat SCCHN, especially recurrent/metastatic disease. Until now, the EGFR signalling pathway has been considered the most important target with respect to new drugs; however, new drugs, such as immunotherapies, are currently under study. As new treatments for SCCHN are developed, the influence of therapies with respect to overall survival, progression free survival and quality of life in patients with this disease is changing.

Novel therapies for meningiomas

Although advances in surgery, radiation therapy and stereotactic radiosurgery have significantly improved the treatment of meningiomas, there remains an important subset of patients who remain refractory to conventional therapy. Treatment with chemotherapeutic agents such as hydroxyurea and alpha-interferon has provided minimal benefit. In this review, the role of newly emerging novel therapies for meningiomas, with a focus on targeted molecular agents, will be discussed.

Treatment of children with high grade glioma with nimotuzumab: a 5-year institutional experience

Brain tumors are a major cause of cancer-related mortality in children. Overexpression of epidermal growth factor receptor (EGFR) is detected in pediatric brain tumors and receptor density appears to increase with tumor grading. Nimotuzumab is an IgG1 antibody that targets EGFR. Twenty-three children with high-grade glioma (HGG) were enrolled in an expanded access program in which nimotuzumab was administered alone or with radio-chemotherapy. The mean number of doses was 39. Nimotuzumab was well-tolerated and treatment with the antibody yielded a survival benefit: median survival time was 32.66 mo and the 2-y survival rate was 54.2%. This study demonstrated the feasibility of prolonged administration of nimotuzumab and showed preliminary evidence of clinical benefit in HGG patients with poor prognosis.

Epidermal growth factor receptor targeting in cancer: a review of trends and strategies

The epidermal growth factor receptor (EGFR) is a cell-surface receptor belonging to ErbB family of tyrosine kinase and it plays a vital role in the regulation of cell proliferation, survival and differentiation. However; EGFR is aberrantly activated by various mechanisms like receptor overexpression, mutation, ligand-dependent receptor dimerization, ligand-independent activation and is associated with development of variety of tumors. Therefore, specific EGFR inhibition is one of the key targets for cancer therapy. Two major approaches have been developed and demonstrated benefits in clinical trials for targeting EGFR; monoclonal antibodies (mAbs) and tyrosine kinase inhibitors (TKIs). EGFR inhibitors like, cetuximab, panitumumab, etc. (mAbs) and gefitinib, erlotinib, lapatinib, etc. (TKIs) are now commercially available for treatment of variety of cancers. Recently, many other agents like peptides, nanobodies, affibodies and antisense oligonucleotide have also shown better efficacy in targeting and inhibiting EGFR. Now a days, efforts are being focused to identify molecular markers that can predict patients more likely to respond to anti-EGFR therapy; to find out combinatorial approaches with EGFR inhibitors and to bring new therapeutic agents with clinical efficacy. In this review we have outlined the role of EGFR in cancer, different types of EGFR inhibitors, preclinical and clinical status of EGFR inhibitors as well as summarized the recent efforts made in the field of molecular EGFR targeting.

Nimotuzumab treatment of malignant gliomas

INTRODUCTION

In spite of new alkylating medication and recently accumulated knowledge about genomics, the prognosis of malignant gliomas remains poor. The introduction of single substances interfering with tumour proliferation dynamics has been disappointing and the lessons learned indicate that a complicated network of proliferation needs time consuming, in-depth analysis in order to more specifically treat now distinguishable subgroups of a disease, which too long was thought of as a uniform entity.

AREAS COVERED

The clinical trials using the EGFR antibody nimotuzumab in the treatment of malignant gliomas are reviewed. Pending conformation in future studies the antibody might be part of the treatment of MGMT-negative, EGFR-amplified, not completely resected gliomas of adulthood and juvenile DIPG (pontine gliomas). Upcoming genomic results of the different tumour entities may suggest certain combination partners of the antibody. Recent studies of nimotuzumab indicate the reason for the lack of toxicity, which is the most attractive argument for its clinical use besides modest efficacy.

EXPERT OPINION

We await the final results on the use of the antibody together with vinorelbine and radiation therapy for the therapy of DIPG. Adult patients with MGMT-negative, EGFR amplified, not totally resected GBM may also profit from this combination therapy. TK-inhibitors combined with the antibody and irradiation may be an option for a therapeutic trial in paediatric patients.

Targeting the epidermal growth factor receptor in solid tumor malignancies

The epidermal growth factor receptor (EGFR) is over-expressed, as well as mutated, in many types of cancers. In particular, the EGFR variant type III mutant (EGFRvIII) has attracted much attention as it is frequently and exclusively found on many tumor cells, and hence both EGFR and EGFRvIII have been proposed as valid targets in many cancer therapy settings. Different strategies have been developed in order to either inhibit EGFR/EGFRvIII activity or to ablate EGFR/EGFRvIII-positive tumor cells. Drugs that inhibit these receptors include monoclonal antibodies (mAbs) that bind to the extracellular part of EGFR, blocking the binding sites for the EGFR ligands, and intracellular tyrosine kinase inhibitors (TKIs) that block the ATP binding site of the tyrosine kinase domain. Besides an EGFRvIII-targeted vaccine, conjugated anti-EGFR mAbs have been used in different settings to deliver lethal agents to the EGFR/EGFRvIII-positive cells; among these are radio-labelled mAbs and immunotoxins. This article reviews the current status and efficacy of EGFR/EGFRvIII-targeted therapies.

Nimotuzumab for pediatric diffuse intrinsic pontine gliomas

INTRODUCTION

Diffuse intrinsic pontine gliomas (DIPG) have a poor prognosis: the median survival rate is less than one year. Radiotherapy is the only effective treatment affording an overall survival of 6 - 9 months. So far, no improvement has been achieved with the addition of single/poly-chemotherapy regimens. An urgent need is to advance in this field, from both the biological and the clinical points of view.

AREAS COVERED

Among the few studies providing biological information on DIPG, Gilbertson's group demonstrated a significant increase in EGFR expression. The activity of nimotuzumab, a humanized anti-EGFR monoclonal antibody, was therefore studied within a Phase II trial in 47 relapsing pediatric patients with DIPG and high-grade gliomas, showing an interesting, persistent response, especially in the first group treated. A multicenter exploratory study combining nimotuzumab and radiotherapy showed disease control and an overall patient survival similar to previous experiences along with an improvement in the quality of patient survival and no severe side effects.

EXPERT OPINION

We recommend considering this combination in the armamentarium against DIPG. It might be improved by adding other target drugs/low-toxicity chemotherapy regimens with a synergistic effect with the anti-EGFR component.

Experimental approaches for the treatment of malignant gliomas

Malignant gliomas, which include glioblastomas and anaplastic astrocytomas, are the most common primary tumors of the brain. Over the past 30 years, the standard treatment for these tumors has evolved to include maximal safe surgical resection, radiation therapy and temozolomide chemotherapy. While the median survival of patients with glioblastomas has improved from 6 months to 14.6 months, these tumors continue to be lethal for the vast majority of patients. There has, however, been recent substantial progress in our mechanistic understanding of tumor development and growth. The translation of these genetic, epigenetic and biochemical findings into therapies that have been tested in clinical trials is the subject of this review.

Medical therapies for meningiomas

Meningiomas are the most common primary brain tumor in adults. Although the majority of these tumors can be effectively treated with surgery and radiation therapy, an important subset of patients have inoperable tumors, or develop recurrent disease after surgery and radiotherapy, and require some form of medical therapy. There are increasing numbers of studies evaluating various medical therapies but the results remain disappointing. Chemotherapies and hormonal therapies have been generally ineffective, although somatostatin analogues may have therapeutic potential. There is also increasing interest in targeted molecular therapies. Agents inhibiting platelet derived growth factor receptors and epidermal growth factor receptors have shown little efficacy, but molecular agents inhibiting vascular endothelial growth factor receptors appear to have some promise. As with other tumors, advances in the medical therapies for meningiomas will require improved understanding of the molecular pathogenesis of these tumors, more predictive preclinical models, and efficient mechanisms for conducting clinical trials, given the small population of eligible patients.

Nimotuzumab in pediatric glioma

High-grade gliomas and diffuse brainstem gliomas carry a very poor prognosis despite current therapies, and account together for the largest number of deaths in children with brain tumors. Many of these tumors have been found to overexpress the EGF receptor (EGFR). Nimotuzumab (h-R3) is a humanized monoclonal antibody against the EGFR, and consequently inhibits tyrosine kinase activation. In vitro and in vivo studies have supported the antiproliferative, antiangiogenic, pro-apoptotic and radiosensitizing activities of nimotuzumab. Emerging trials suggest a promising role for nimotuzumab as a therapeutic agent in patients with high-grade gliomas. This review attempts to provide a context for the evolving interest and evidence for nimotuzumab in pediatric glioma.

Detecting and treating cancer with nanotechnology

Nanotechnology offers many opportunities for enhanced diagnostic and therapeutic medicine against cancer and other diseases. In this review, the special properties that result from the nanoscale size of quantum dots, metal colloids, superparamagnetic iron oxide, and carbon-based nanostructures are reviewed and interpreted against a background of the structural and electronic detail that gives rise to their nanotechnologic behavior. The detection and treatment of cancer is emphasized, with special attention paid to the biologic targeting of the disease. The future of nanotechnology in cancer research and clinical practice is projected to focus on 'theranostic' nanoparticles that are both diagnostic and therapeutic by design.

Targeted drug therapy for meningiomas

✓ Although advances in surgery, radiation therapy, and stereotactic radiosurgery have significantly improved the treatment of meningiomas, there remains an important subset of patients whose tumors are refractory to conventional therapy. Treatment with traditional chemotherapeutic agents has provided minimal benefit. In this review, the role of targeted molecular therapies for recurrent or progressive meningiomas is discussed.

Recent progress in immunotherapy for malignant glioma: treatment strategies and results from clinical trials

BACKGROUND

Despite advances in surgical and adjuvant radiation therapy and chemotherapy strategies, malignant gliomas continue to be associated with poor prognoses.

METHODS

We review immune-mediated treatment approaches for malignant glioma and the relevance of recent clinical trials and their outcomes. We specifically address the increasing evidence implicating the role of cytotoxic T cells in ensuring adequate immune-mediated clearance of neoplastic cells and the need for the optimization of therapies that can elicit and support such antitumor T-cell activity.

RESULTS

The poor outcome of this disease has spurred the search for novel experimental therapies that can address and overcome the root biological phenomena associated with the lethality of this disease. The use of immunotherapy to bolster the otherwise impaired antitumor immune responses in glioma patients has received increasing attention.

CONCLUSIONS

An effective treatment paradigm for malignant gliomas may eventually require a multifaceted approach combining two or more different immunotherapeutic strategies. Such scenarios may involve the use of local cytokine gene therapy to enhance glioma-cell immunogenicity in conjunction with dendritic cell-based active vaccination to stimulate systemic tumoricidal T-cell immunity. Given the heterogeneity of this disease process and the potential risk of immunoediting out a selected, treatment-refractory tumor cell population, the concurrent use of multiple modalities that target disparate tumor characteristics may be of greatest therapeutic relevance.

Emerging treatments and gene expression profiling in high-risk medulloblastoma

The past decades have seen an increase in the survival rates of patients with standard-risk medulloblastoma. Efforts have, therefore, been focused on obtaining better results in the treatment of patients with high-risk tumors. In addition to consolidated therapies, novel approaches such as small molecules, monoclonal antibodies, and antiangiogenic therapies that aim to improve outcomes and quality of life are now available through new breakthroughs in the molecular biology of medulloblastoma. The advent of innovative anticancer drugs tested in brain tumors has important consequences for personalized therapy. Gene expression profiling of medulloblastoma can be used to identify the genes and signaling transduction pathways that are crucial for the tumorigenesis process, thereby revealing both new targets for therapy and sensitive/resistance phenotypes. The interpretation of microarray data for new treatments of patients with high-risk medulloblastoma, as well as other poor prognosis tumors, should be developed through a consensus multidisciplinary approach involving oncologists, neurosurgeons, radiotherapists, biotechnologists, bioinformaticists, and other professionals.

Rational bases for the development of EGFR inhibitors for cancer treatment

Growth factor receptors and their ligands not only regulate normal cell processes but have been also identified as key regulators of human cancer formation. The epidermal growth factor receptor (EGFR/ErbB1/HER1) belongs to the ErbB/HER-family of tyrosine kinase receptors (RTKs). These trans-membrane proteins are activated following binding with peptide growth factors of the EGF-family of proteins. Several evidences suggest that cooperation of multiple ErbB receptors and ligands is required for the induction of cell transformation. In this respect, EGFR, upon activation, sustains a complex and redundant network of signal transduction pathways with the contribution of other trans-membrane receptors. EGFR has been found to be expressed and altered in a variety of malignancies and clearly it plays a significant role in tumor development and progression, including cell proliferation, regulation of apoptotic cell death, angiogenesis and metastatic spread. Moreover, amplification of the EGFR gene and mutations in the EGFR tyrosine kinase domain have been recently reported in human carcinomas. As a result, investigators have developed approaches to inhibit the effects of EGFR activation, with the aim of blocking tumor growth and invasion. A number of agents targeting EGFR, including specific antibodies directed against its ligand-binding domain and small molecules inhibiting its tyrosine kinase activity are either in clinical trials or are already approved for clinical treatment. This article reviews the EGFR role in carcinogenesis and tumor progression as rational bases for the development of specific therapeutic inhibitors.

Inhibiting kinases in malignant gliomas

Advances in the understanding of glioma pathogenesis have led to increasing interest in the development of targeted molecular agents, and especially kinase inhibitors, for treatment of malignant gliomas. Protein kinases are a large family of enzymes that function as key regulators of cellular signaling pathways governing diverse functions, such as cell proliferation, growth, differentiation, invasion, angiogenesis and apoptosis in malignant gliomas. Preliminary clinical results with kinase inhibitors suggest that they are generally well-tolerated but have shown only modest activity. However, valuable information was obtained from these early clinical trials that will help the future development of these agents. This article reviews the important protein kinases in malignant gliomas, summarizes the existing clinical development of kinase inhibitors and discusses strategies to improve their effectiveness.

Emerging monoclonal antibody therapies for malignant gliomas

An improved understanding of the molecular characteristics of gliomas has led to the recognition of potential antigen targets and monoclonal antibody (mAb) therapies for these challenging tumors. The design of glioma mAbs--including species, construct, immunoglobulin isotype and conjugate--affects their delivery, efficacy and toxicities. mAbs that are under study for glioma therapy include some mAbs that are currently approved for use in the treatment of other cancers, as well as novel molecules. Although the greatest experience so far is with locally administered, radiolabeled mAbs, systemic unconjugated mAbs are being studied increasingly for glioma treatment. Previous experience with mAbs in other malignancies may provide guidance for their use in the treatment of CNS malignancies.

Active antimetastatic immunotherapy in Lewis lung carcinoma with self EGFR extracellular domain protein in VSSP adjuvant

The epidermal growth factor receptor (EGFR) plays a central role in regulating neoplastic processes. The EGFR overexpression in many human epithelial tumors has been correlated with disease progression and bad prognosis. Passive EGFR-directed immunotherapy, but not active specific approaches, has already been introduced in medical oncology practice. Then we wonder if mice immunization with the extracellular domain of murine EGFR (mEGFR-ECD) in adjuvants can circumvent tolerance to self EGFR, by inducing an immune response with consequent antitumor effect. The present study demonstrated that despite mEGFR expression in thymus, strong DTH response was induced by inoculation of mice with the mEGFR-ECD. This self-immunization, using both CFA and very small sized proteoliposomes from Neisseria meningitidis (VSSP), promoted highly specific IgG titers, predominantly IgG2a and IgG2b. Sera from mice immunized with mEGFR-ECD/VSSP not only recognized EGFR+ tumor cell lines by FACS, but also inhibited their in vitro growth, even in the absence of complement. Noteworthy, vaccination of mice with mEGFR-ECD/VSSP stimulated a potent antimetastatic effect in the EGFR+ Lewis lung carcinoma model, while reproduction-associated side effects were absent. Curiously, mice immunized with the human EGFR-ECD (Her1-ECD) in VSSP though induced highly specific IgG antibodies with strong in vitro cytotoxic effect over EGFR+ human cell lines, showed low cross-reactivity with the mEGFR-ECD. These results further encouraged the development of the Her1-ECD/VSSP vaccine project for patients with EGFR+ tumors.

Clinical implications of the mechanism of epidermal growth factor receptor inhibitors

Novel therapeutic agents that target the epidermal growth factor receptor (EGFR) constitute an important addition to the therapeutic armamentarium for the treatment of metastatic disease. EGFR-targeted agents currently approved by the U.S. Food and Drug Administration include cetuximab, a monoclonal antibody for the treatment of colorectal cancer; and the small-molecule EGFR tyrosine kinase inhibitor (TKI) erlotinib for the treatment of nonsmall cell lung cancer (NSCLC) and pancreatic cancer. Approval of the TKI gefitinib for NSCLC recently was withdrawn. Although both classes of anti-EGFR agents target the same receptor, substantial distinctions regarding their mechanism significantly affect dosing requirements, toxicity profiles, and their use as combination agents.

Targeted molecular therapy for malignant gliomas

Advances in our understanding of the molecular changes and resultant cellular effects in malignant glioma are expanding the opportunities for novel targeted therapies. At present, chemotherapy and radiation followed by chemotherapy with nonselective cytotoxic agents is emerging as a standard treatment option for patients with malignant glioma. Unfortunately significant improvements in response and survival have not occurred for the majority of patients. The continued improvement in patient outcomes will require the incorporation of glioma-specific therapies either in the form of compounds specifically targeted to glioma-specific receptors or that inhibit signaling pathways promoting glioma survival and progression.

Transient expression in tobacco leaves of an aglycosylated recombinant antibody against the epidermal growth factor receptor

When generating stably transformed transgenic plants, transient gene expression experiments are especially useful to rapidly confirm that the foreign molecule of interest is correctly assembled and retains its biological activity. TheraCIM(R) (CIMAB S.A., Havana) is a recombinant humanized antibody against the Epidermal Growth Factor receptor (EGF-R), now in clinical trials for cancer therapy in Cuba and other countries. An aglycosylated version (Asn 297 was mutated for Gln 297) of this antibody was transiently expressed in tobacco leaves after vacuum-mediated infiltration of recombinant Agrobacterium tumefaciens that carried a binary plasmid bearing the antibody heavy and light chain genes and plant regulation signals. Protein extracts from "agroinfiltrated" leaves were tested by ELISA and Western blot, showing that the fully assembled antibody was accumulated in plant tissues. The absence of plant specific glycans did not interfere in the assembling or in the activity of the plantibody, as demonstrated in this work. Indirect immunofluorescence demonstrated that the aglycosylated antibody expressed in plants recognizes the EGF-R expressed on the surface of A431 human tumor culture cells.

Perspectives of Cellular and Molecular Neurosurgery

Therapeutic efforts for human glial tumors have over the past years been redirected towards a compartmental treatment concept. The diffusely infiltrative nature of the disease calls for therapeutic agents to reach single cells far beyond the focus of attention which present therapies like surgery and radiation are able to treat. Specific drug discovery approaches which seek to define targets which are specific for gliomas have generated therapeutic options which allow for a highly selective development of new reagents. Combined with new modalities for compartmental drug delivery, systemic complications might be reduced and advantage taken of a compartmental specificity of a target which otherwise in the context of systemic application would not be as specific or burdened with side effects. From the present status of therapeutic developments in neuro-oncology it can be expected that a sufficient number of drug targets emerge which can be exploited by means of interstitial or intracavitary delivery, which are not neurotoxic and which may even be imaged in their action with the new metabolic imaging modalities. Convection enhanced delivery, conditionally replicating oncolytic viruses and motile, genetically engineered neural stem cells all seem to fulfill the distribution requirements which an effective therapeutic for gliomas will need to overcome the very limited efficacy which surgery, conventional chemotherapy and radiation have to offer. Whereas the genomics based discovery approaches are not specific for neuro-oncology, the development of delivery strategies is highly specific for the central nervous system, thus creating a unique set of organ and disease specific therapies.

EPIDERMAL GROWTH FACTOR RECEPTOR ANTAGONISTS: NOVEL THERAPY FOR THE TREATMENT OF HIGH-GRADE GLIOMAS

Overactivation of epidermal growth factor receptor (EGFR) signaling has been recognized as an important step in the pathogenesis and progression of multiple forms of cancer of epithelial origin. This knowledge has led to a surge of interest in novel anticancer therapies targeting key constituents of the EGFR signal transduction pathway. Several molecular strategies have been developed recently to modulate either EGFR or the downstream signal beyond the cell surface receptor. The important role of aberrant EGFR signaling in the progression of malignant gliomas makes EGFR-targeted therapies of particular interest in this form of cancer. The use of anti-EGFR therapies against malignant brain tumors, although in its infancy, promises to yield exciting results as these new drugs probably will enhance the usefulness of existing therapies.

Immunization with a plant-produced colorectal cancer antigen

Cancer vaccination has become an important focus of oncology in recent years. Active immunization with tumor-associated antigens such as colorectal cancer antigen GA733-2 is thought to potentially overcome the reoccurrence of metastasis. As recombinant protein production in bioreactors is costly and subject to growing safety concerns, we tested plants as an alternative for the expression of a potential colorectal cancer vaccine. Comparing colorectal cancer antigen GA733-2 produced in tobacco plants with the same antigen produced in insect cell culture, we found a similar humoral immune response to injection of either of the two antigen preparations into mice. Some minor differences were observed in the cellular response that might be due to impurities. Our studies compare for the first time, immunization with the same antigen expressed in either plants or insect cell culture. This will provide important data for use of plants as production systems of therapeutics.

Interleukin-13 receptor-directed cytotoxin for malignant glioma therapy: from bench to bedside

Central nervous system malignant neoplasias, in particular, glioblastoma multiforme (GBM) have defied all current therapeutic modalities. New therapies involving tumor targeting approach are being explored. This approach relies on the identification of unique or over-expressed cell surface receptors or antigens on tumor cells. In that regard, we have identified receptor for an immune regulatory cytokine, interleukin-13 (IL-13), which is over-expressed on human malignant glioma cell lines and primary tumor cell cultures. To target IL-13 receptors (IL-13R) for cancer therapy, we have developed a recombinant fusion protein composed of IL-13 and a mutated form of Pseudomonas exotoxin (IL13-PE38QQR or IL-13 cytotoxin). The IL-13 cytotoxin was found to be highly selective and potent in killing human GBM cells in vitro while normal cells including immune cells, endothelial cells and normal brain cells were generally spared the cytotoxic effect of IL-13 cytotoxin. This is because these cells either expressed none or expressed low levels of IL-13R. Consistent with in vitro cytotoxic activity, IL-13 cytotoxin mediated remarkable anti-tumor activity to human glioma in animal xenograft models. The direct injection of IL-13 cytotoxin into subcutaneous human GBM tumors grown in nude mice produced complete and durable regression of established tumors. Intravenous and intraperitoneal administration of IL-13 cytotoxin also reduced tumor burden significantly with fewer complete responders. All animals tolerated therapy well with minimal toxicity to vital organs. Pre-clinical safety and toxicity studies were performed in mice, rats and monkeys. Systemic administration of IL-13 cytotoxin appeared to be well tolerated at high doses (up to 50 microg/kg). Intrabrain parenchyma administration of IL-13 cytotoxin at doses up to 100 microg/ml was very well tolerated without any evidence of gross or microscopic necrosis, whereas at 500 microg/ml dose, localized necrosis was observed in normal rat brain. Based on these encouraging pre-clinical studies, three Phase I/II clinical trials in adults with malignant glioma have been initiated. The first clinical trial involves convection-enhanced delivery (CED) of IL-13 cytotoxin into recurrent malignant glioma. This route of IL-13 cytotoxin administration appears to be fairly well tolerated with no neurotoxicity. The second clinical trial involves infusion of IL-13 cytotoxin by CED following tumor resection. The initial stage of the second study assessed histologic effect of drug administered prior to resection. In third one, IL-13 cytotoxin is infused by CED followed by tumor resection. All three clinical trials are currently ongoing.

Radioinmunolocalización de tumores de cabeza y cuello con un nuevo anticuerpo monoclonal contra el receptor del EGF. Resultados preliminares

OBJECTIVE

To show the results of Radioimmunodetection (RID) using Cuban monoclonal antibody (MoA) anti-egf-ior-egf-r3 labeled with 99mTc for the detection of primary tumors and/or metastases of head and neck epithelial malignant tumors.

MATERIAL AND METHODS

Thirteen patients aged from 16-62 years (mean: 54.8 years) with primary tumors and metastases in the regional cervical lymph nodes were retrospectively evaluated. The labelling dose was 1480-2220 MBq (40-60 mCi). Planar images were performed after 10 minutes and together with SPECT images after 18-24 hours following MoA administration. The matrix was 128 x 128. SPECT images were reconstructed using the Butterworth 4/16 filter. A positive result was defined when the lesions were visualized.

RESULTS

RID localized 11 of the known primary tumors in the 13 patients studied. In the two other patients, in whom the primary tumor site was unknown, cervical lymph node metastases were found. The results of 3 of the RID were false negative but in the other 10, RID was able to localize the primary tumor and cervical lymph node metastases. Sensitivity was 77 % and the predictive positive value was 100 %.

CONCLUSIONS

The results of this study show that the Cuban MoA ior-egf-r3 can be employed for RID of primary head and neck tumors and their metastases. The radiation dose is adequate for RID.

Recent advances in the molecular genetics of primary gliomas

Primary brain tumors, particularly glioblastomas, remain a challenge for oncology. Uncontrolled cellular proliferation, lack of apoptosis, invasion, and angiogenesis are among the biologic processes that render these tumors both aggressive and difficult to treat. An understanding of the genetics and molecular events regulating these aggressive tumors is beginning to emerge, partly because of recent knowledge in genomics, gene expression analysis, and mouse tumor models. As a result, it is now generally accepted that brain tumors, particularly those arising from cells of glial lineage, result from stepwise accumulation of deleterious genetic alterations. Several genetic abnormalities have been described, and current research is aimed at elucidating their causal association with brain tumor formation and progression. The purpose of this review is to summarize some of the most important recently published findings on the molecular genetics of primary gliomas.

Pharmacological evaluation of humanized anti-epidermal growth factor receptor, monoclonal antibody h-R3, in patients with advanced epithelial-derived cancer

Epidermal growth factor receptor (EGFR) overexpression has been detected in many tumors of epithelial origin, and it is often associated with tumor growth advantages and poor prognosis. h-R3 is a genetically engineered humanized antibody (mAb) that recognizes an epitope located in the extracellular domain of human EGFR. The antibody exhibited potent in vitro and in vivo antitumor effect on EGFR overexpressing cell lines. To study safety, pharmacokinetics, and biodistribution, 12 patients with advanced epithelial-derived tumors received single intravenous infusion of h-R3 at four dose levels. Safety evaluation was made according to World Health Organization toxicity criteria. For biodistribution, 3 mg of the total dose were labeled with Technetium and then pooled with the rest of the dose. Anterior and posterior whole-body images were acquired using a gamma camera. Blood samples were taken for pharmacokinetics, antiidiotypic response, and for soluble EGFR detection. After hR3 administration, no evidence of severe toxicity was observed. Secondary reactions were mild and moderate and mainly consisted of tremors, fever, and vomiting. No anaphylactic or skin reactions were detected. Qualitative analysis of whole-body images showed that the liver had the highest mAb uptake. Pharmacokinetic analysis revealed that elimination half-lives and the AUC increased linearly with dose, while total body clearance decreased when increasing doses of h-R3. No relation between shed EGFR and mAb clearance was found. No antiidiotypic response against h-R3 was detected. Several phase II trials are now underway to evaluate the efficacy of h-R3 in the treatment of advanced cancer patients.

An update on epidermal growth factor receptor inhibitors

The epidermal growth factor receptor (EGFR) is part of a family of plasma membrane receptor tyrosine kinases that control many important cellular functions, from cell growth and proliferation to cell death. Dysregulation of the EGFR signal transduction pathway has been implicated in tumorigenesis and cancer progression, making it a clinically relevant target for novel anticancer treatments. This paper reviews recent progress in the development of cancer therapies that are directed toward particular aspects of the extracellular and intracellular domains of EGFR. Promising new compounds in the advanced stages of clinical testing are emphasized.